Chaumont-en-Vexin Wastewater Treatment Plant, Hauts-de-France, France

The Chaumont-en-Vexin wastewater treatment plant is located in the commune of Chaumont-en-Vexin, within the Oise department of Hauts-de-France, France. The facility serves a population of approximately 4,148 and is classified as a small agglomeration under French and EU regulations. The plant employs advanced treatment processes, which go beyond the secondary treatment required by the EU Urban Waste Water Treatment Directive (91/271/EEC) for agglomerations of this size. With a designed capacity of 5,000 m³/day and an average daily discharge of 740 m³, the plant operates well below its capacity, indicating room for future growth or seasonal variations. The treated effluent is discharged into local watercourses that eventually drain into the Seine River basin, which flows into the English Channel. The plant plays a key role in protecting the region's water quality, supporting aquatic life, and meeting the environmental objectives of the Seine-Normandy water agency.

The plant discharges into the local watershed, which is part of the Seine River basin. The Seine flows through Paris and into the English Channel, supporting diverse aquatic ecosystems and providing drinking water for millions. The advanced treatment helps reduce nutrient loads, protecting downstream waters from eutrophication and maintaining ecological balance in the Seine estuary.